Application Of Gas Ultrasonic Spectrum In The Measurement Of Hydrogen Concentration

As a kind of efficient pollution-free clean energy resource with a sustainable development prospect,hydrogen has potential to solve the energy crisis.However,hydrogen is highly flammable and may also cause serious security issue as leaking.Aiming at the issues of low accuracy,high cost and poor repeatability that exist in current hydrogen sensors,this paper proposes an acoustic method based on the measurement of both sound velocity and absorption coefficient for hydrogen concentration detection in three component gases.The major work and results of this paper are as follows:We analysis the molecular collision and energy transfer model in mixed gases based theoretically on the velocity spectrum and absorption spectrum of hydrogen combined with Dain-Lueptow(D-L)theory,and come to the corresponding relation of sound velocity,sound absorption and acoustic frequency,gas concentrations of each component.Based on the simulation results of the corresponding relation of sound velocity,sound absorption and acoustic frequency,gas concentrations of each component,we establish the theoretical model.The calculation results reveal that there exists an absorption peak in the frequency curve of acoustic absorption coefficient,through which the theoretical model is able to be extended to the hydrogen concentration measurement in four component gases.At the same time,the influence of environmental factors such as temperature and humidity on the measurement accuracy is calculated.To solve the temperature influence on measurement accuracy,linear compensation algorithm is proposed,which improves the detection limit of more than 250 ppm.We set up an experimental scheme of hydrogen concentration measurement in two or three component gases.The experimental results of sound velocity and sound absorption coefficient reveal that the measuring accuracy of hydrogen concentration is 250 ppm in two component gases and 1100 ppm in three component gases,which are higher than expectation.Various factors such as temperature,humidity,pressure and air tightness are further discussed as the error sources of the system,and quantitatively analyzed.In order to verify the frequency characteristics of sound absorption coefficient in hydrogen,experiments are carried out and prove that the measured sound absorption coefficient is consistent with the theoretical calculation in general.Based on the theoretical modeling and calculation,experimental measurements and error analysis of sound speed and sound absorption characteristics in three component gases are conducted.This paper discusses the feasibility of ultrasonic spectrum detection approach for hydrogen concentration measurements,which provides a reference for the high-precision measurement approach for hydrogen in acoustics.